The revolution has begun! Web video will be freed from the shackles of the MPEG-LA and the dreaded claws of patents and incomprehensible licenses! Sorry, I got a little carried away there. Anywho, YouTube has announced all new videos uploaded to the site will be transcoded into WebM, and that the most important part of the site's catalogue is already available in WebM.

"You do not understand copyright licenses and the clauses in WebM license: they cannot retroactively change license terms for the code and software that has already been released, only for NEW releases.

Ups, I wasn't clear enough. That is exactly what would allow the web to use previous versions of VP8, Vorbis and Matroska together, as in my example, I just wasn't clear enough.

There are different licenses for different aspects of involvement with WebM. If you want to contribute to Google's software implementation of WebM, there are contributor licenses for individuals and for corporations.

If you want to write your own implementation, then your code is your code and it is not subject to Google's permission for Google's WebM codebase. The only thing you need to worry about if you want to write your own code is permission to use the WebM bitstream format. The license terms for that are, in essence, as follows:

http://www.webmproject.org/license/bitstream/"Google hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer implementations of this specification where such license applies only to those patent claims, both currently owned by Google and acquired in the future, licensable by Google that are necessarily infringed by implementation of this specification."

Note in particular the use of the words "irrevocable" and "perpetual".